This is a full size milling enclosure for my knee mill, that I made from 1/4" polycarbonate. If you want to know how to bend polycarbonate, I bent it using a propane torch. Note that you have to be careful and not overheat any area, or it will start bubbling. It was good enough for my needs, anyway. I also tried a plastic heating strip, and it was useless.
The front piece is, obviously, removable. I cut locking tabs in the front and side pieces, that lock it in position when installed.